Embolic protection device

ABSTRACT

An embolic protection device for use in a patient&#39;s blood vessel, such as the aorta, has an approximately cylindrical outer structure made of a filter mesh material and an approximately conical inner structure also made of a filter mesh material. On the downstream end of the embolic protection device, the wider end of the conical inner structure is joined to the cylindrical outer structure. The upstream end of the embolic protection device is open for blood to flow between the conical inner structure and the cylindrical outer structure. The space between the conical inner structure and the cylindrical outer structure defines a collection chamber for captured emboli. The narrow upstream end of the conical inner structure has a catheter port with a resilient seal that is sized for passage of a catheter shaft. The filter mesh material may be self-supporting or it may be supported on a resilient-framework or an inflatable framework.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/532,630 (Attorney Docket No. 41959-704.831), filed Apr. 26, 2010,which is a National Stage Application of PCT/US2007/24558 (AttorneyDocket No. 41959-704.601), filed Nov. 29, 2007, which claims the benefitof U.S. Provisional Application No. 60/861,687 (Attorney Docket No.41959-704.101), filed Nov. 29, 2006, the full disclosures of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to apparatus and methods for providingembolic protection in a patient's vascular system. In particular, itrelates to an embolic protection device that can be deployed in apatient's aorta to protect the aortic arch vessels and downstream organsfrom potential emboli. The embolic protection device can be usedacutely, for example for embolic protection during cardiac surgery andinterventional cardiology procedures, or it can be implanted for chronicembolic protection, for example from cardiogenic emboli or emboli fromruptured or vulnerable aortic plaque.

Cerebral embolism is a known complication of cardiac surgery,cardiopulmonary bypass and catheter-based interventional cardiology andelectrophysiology procedures. Embolic particles, which may includethrombus, atheroma and lipids, may become dislodged by surgical orcatheter manipulations and enter the bloodstream, embolizing in thebrain or other vital organs downstream. Other sources of potentialemboli include cardiogenic emboli, such as thrombus that results fromchronic atrial fibrillation, and emboli from ruptured or vulnerableaortic plaque. Cerebral embolism can lead to neuropsychologicaldeficits, stroke and even death. Other organs downstream can also bedamaged by embolism, resulting in diminished function or organ failure.Prevention of embolism would benefit patients and improve the outcome ofthese procedures.

Given that the sources of potential emboli can be acute or chronic, itwould be advantageous to provide an embolic protection device that caneither be used acutely, for example for embolic protection duringcardiac surgery and interventional cardiology procedures, or that can beimplanted for chronic embolic protection, for example from cardiogenicemboli or emboli from ruptured or vulnerable aortic plaque. A furtheradvantage would be realized by providing an embolic protection devicethat can be implanted without interfering with transluminal aorticaccess for performing future surgeries and other interventional ordiagnostic procedures. Another advantage would come from providing anembolic protection device that can be retrieved and removed from thepatient after the necessity for it has passed. Yet another advantagewould come from providing an embolic protection device that can bedeployed and retrieved using minimally invasive techniques.

Previous devices for preventing cerebral embolism are described in thefollowing patents and patent applications, which are hereby incorporatedby reference: U.S. Pat. App. 20040215167 Embolic protection device, PCTApp. WO/2004/019817 Embolic protection device, U.S. Pat. No. 6,371,935Aortic catheter with flow divider and methods for preventing cerebralembolization, U.S. Pat. No. 6,361,545 Perfusion filter catheter, U.S.Pat. No. 6,254,563 Perfusion shunt apparatus and method, U.S. Pat. No.6,139,517 Perfusion shunt apparatus and method, U.S. Pat. No. 6,537,297Methods of protecting a patient from embolization during surgery, U.S.Pat. No. 6,499,487 Implantable cerebral protection device and methods ofuse, U.S. Pat. No. 5,769,816 Cannula with associated filter, U.S. Pat.App. 20030100940 Implantable intraluminal protector device and method ofusing same for stabilizing atheromas.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an embolic protection device according to the presentinvention in an expanded or deployed condition.

FIG. 2 shows the embolic protection device of FIG. 1 in an undeployed orretracted condition.

FIG. 3 shows an enlarged view of a catheter port for use in the embolicprotection device of FIG. 1.

FIG. 4 shows another embodiment of a catheter port for use in theembolic protection device of FIG. 1.

FIG. 5 shows another embodiment of a catheter port for use in theembolic protection device of FIG. 1.

FIG. 6 shows another embodiment of a catheter port for use in theembolic protection device of FIG. 1.

FIG. 7 shows an embolic protection device in an undeployed conditionbeing inserted into a patient's aortic arch.

FIG. 8 shows the embolic protection device implanted in a patient'saortic arch.

FIG. 9 shows a guidewire passing through the catheter port of animplanted embolic protection device.

FIG. 10 shows a catheter-based interventional procedure being performedwith the implanted embolic protection device in place.

FIG. 11 shows an embolic protection device in a retracted condition forremoval from the patient's aorta.

FIG. 12 shows an inflatable embodiment of an embolic protection devicein an uninflated condition.

FIG. 13 shows the embolic protection device of FIG. 12 in an inflatedcondition.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows an embolic protection device 100 according to the presentinvention in an expanded or deployed condition. The embolic protectiondevice 100 has an approximately cylindrical outer structure 102 made ofa filter mesh material and an approximately conical inner structure 104also made of a filter mesh material. On the downstream end 110 of theembolic protection device 100, the wider end of the conical innerstructure 104 is joined to the cylindrical outer structure 102. Theupstream end 108 of the embolic protection device 100 is open for bloodto flow between the conical inner structure 104 and the cylindricalouter structure 102 as indicated by the arrow in FIG. 1. The spacebetween the conical inner structure 104 and the cylindrical outerstructure 102 defines a collection chamber 103 for captured emboli.

The filter mesh material of the conical inner structure 104 and thecylindrical outer structure 102 may be made of knitted, woven ornonwoven fibers, filaments or wires and will have a pore size chosen tostop emboli above a certain size to pass through. The filter meshmaterial may be made of a metal, a polymer or a combination thereof andmay optionally have an antithrombogenic coating on its surface. Thefilter mesh material of the conical inner structure 104 and thecylindrical outer structure 102 may have the same pore size or they mayhave different pore sizes. For example, the filter mesh material of theconical inner structure 104 and the cylindrical outer structure 102 mayboth have a pore size in the range of approximately 1 mm to 0.1 mm oreven smaller, depending on whether it is intended to capture macroembolionly or microemboli as well. Alternatively, the filter mesh material ofthe cylindrical outer structure 102 may have a pore size to stopmicroemboli as small as 0.1 mm and the filter mesh material of theconical inner structure 104 may have a pore size to stop macroembolilarger than 1 mm. In another alternate embodiment, a portion of thecylindrical outer structure 102 configured to be positioned away fromthe aortic arch vessels may be constructed of an impermeable materialrather than the filter mesh material.

The narrow upstream end of the conical inner structure 104 has acatheter port 106 with a resilient seal that is sized for passage of acatheter shaft.

FIG. 2 shows the embolic protection device 100 of FIG. 1 in anundeployed or retracted condition. A delivery catheter 124 is insertedthrough the catheter port 106 of the embolic protection device 100.Typically, the delivery catheter 124 will be constructed with aninternal lumen 125 that terminates in a guidewire port 126 at the distalend of the catheter 124. Optionally, a tubular outer delivery sheath 130may be used to maintain the embolic protection device 100 in theundeployed condition. The delivery catheter 124 may optionally include ashoulder 128 positioned proximal to the embolic protection device 100 tomaintain the position of the embolic protection device 100 on thedelivery catheter 124 as the delivery sheath 130 is withdrawn duringdeployment. Alternatively, a pusher catheter (not shown) that fits inbetween the delivery catheter 124 and the delivery sheath 130 may beused to facilitate deployment.

Optionally, when the embolic protection device 100 is intended to beused for embolic protection during a catheter-based diagnostic orinterventional procedure, the delivery catheter 124 may be configured asa diagnostic catheter, a guiding catheter or therapeutic catheter.

The embolic protection device 100 will preferably be self-supporting inthe deployed condition. This can be accomplished with a variety ofdifferent constructions. In one example, the conical inner structure 104and the cylindrical outer structure 102 can be constructed with aresilient filter mesh material that can be compressed into theundeployed condition and will self-expand into the deployed condition.Alternatively, the filter mesh can be supported by a framework thatincludes an upstream hoop 112, a downstream hoop 114 and one or morelongitudinal struts 113 that form the cylindrical outer structure 102and one or more angled struts 107 that, together with the downstreamhoop 114, form the conical inner structure 104. In an alternateconstruction, the upstream end of the conical inner structure 104 can besupported by one or more radial struts connected to the upstream hoop112, obviating the need for the angled struts 107. (FIG. 13 shows anexample of a framework that uses radial struts 172, 174 to support theconical inner structure 104.) The hoops and struts may be made of aresilient metal and/or polymer material to make a self-expandingframework or a malleable or plastically deformable material to make aframework that can be expanded with an inflatable balloon or otherexpansion mechanism (not shown). Alternatively, the framework can bemade of a shape-memory material that can be used to deploy and/orretract the embolic protection device 100. The filter mesh supported onthe framework can be resilient, flaccid or plastically deformable.Hybrid constructions that combine features of the self-supportingstructure and the frame-supported structure may also be used. Hybriddeployment methods, such as balloon-assisted self-expansion can also beutilized.

The embolic protection device 100 may be constructed with the conicalinner structure 104 and the cylindrical outer structure 102 havingapproximately the same longitudinal dimensions, as shown in thedrawings. Alternatively, the conical inner structure 104 or thecylindrical outer structure 102 can be made longer or shorter withoutadversely affecting the performance of the product. In another alternateconstruction, the cylindrical outer structure 102 can be made slightlyconical with the larger end of the cone on the upstream side.

Optionally, the embolic protection device 100 may include features toassist in retracting the device for retrieval from the patient's aorta.For example, the upstream end 108 and the downstream end 110 of theembolic protection device 100 may be constructed with retraction members116, 120 that are configured like purse strings or lassos around thecircumference of the cylindrical outer structure 102. A pull loop 122 orother graspable structure near the downstream end 110 of the embolicprotection device 100 is connected to the retraction members 116, 120 byone or more connecting members 113. Optionally, two separate pull loops122 may be provided for selectively retracting the upstream anddownstream retraction members 116, 120. The retraction members 116, 120and connecting members 113 may be made of suture, wire, plastic filamentor a combination of these materials. In an alternate construction, thesupport hoops 112, 114 described above may also be configured to serveas the retraction members 116, 120.

FIG. 3 shows an enlarged view of a catheter port 106 for use in theembolic protection device 100. The catheter port 106 is located at thenarrow upstream end of the conical inner structure 104, as shown inFIG. 1. The catheter port 106 has a resilient seal that is sized forpassage of a catheter shaft. The resilient seal of the catheter port 106does not need to make a perfect hemostatic seal when the catheter port106 is empty or when there is a catheter or guidewire through thecatheter port 106; the only requirement is that it should exclude thepassage of emboli above a certain size. In this embodiment, theresilient seal is in the form of an elastomeric disk or ring 131 with ahole 132 through the center that can stretch 132′ to accommodate a rangeof catheter sizes. The elastomeric disk 131 will preferably have a lowcoefficient of friction and/or a lubricious coating so that movement ofa catheter through the catheter port 106 will not jostle or dislodge theembolic protection device 100.

FIG. 4 shows another embodiment of a catheter port 106 for use in theembolic protection device 100 of FIG. 1. In this embodiment, theresilient seal is in the form of an elastomeric disk 133 with a slit 134through the center that can stretch 134′ to accommodate a range ofcatheter sizes. The elastomeric disk 133 will preferably have a lowcoefficient of friction and/or a lubricious coating so that movement ofa catheter through the catheter port 106 will not jostle or dislodge theembolic protection device 100.

FIG. 5 shows another embodiment of a catheter port 106 for use in theembolic protection device 100 of FIG. 1. In this embodiment, theresilient seal is in the form of an elastomeric disk 135 with a flap ortrap door 136 through the center that can open by bending in theupstream direction to allow passage of a catheter. Optionally, theresilient seal may also include a second elastomeric disk 137 on thedownstream side with a hole 138 through it slightly smaller than thetrap door 136 that will provide a sliding seal around a catheter shaftand will support the flap or trap door 136 against blood pressure whileit is in the closed position. The elastomeric disks 135, 137 willpreferably have a low coefficient of friction and/or a lubriciouscoating so that movement of a catheter through the catheter port 106will not jostle or dislodge the embolic protection device 100.

FIG. 6 shows another embodiment of a catheter port 106 for use in theembolic protection device 100 of FIG. 1. In this embodiment, theresilient seal is in the form of a plurality of resilient flaps 140 thatoverlap or interdigitate to form a seal, but that can bend back to allowpassage of a catheter. The example shown has four approximatelysemicircular flaps 140 that overlap one another to form a seal. Othernumbers and geometries of flaps are also possible. The resilient flaps140 will preferably have a low coefficient of friction and/or alubricious coating so that movement of a catheter through the catheterport 106 will not jostle or dislodge the embolic protection device 100.

FIG. 7 shows an embolic protection device 100 in an undeployed conditionmounted on a delivery catheter 126 being inserted over a guidewire 142into a patient's aortic arch. Optionally, a delivery sheath 130 may beused to hold the embolic protection device 100 in the undeployedposition. Once the embolic protection device 100 is at the desiredlocation, the embolic protection device 100 is deployed, for example bywithdrawing the delivery sheath 130 and allowing the embolic protectiondevice 100 to expand. If the delivery catheter 126 is in the form of adiagnostic or therapeutic catheter, the catheter 126 can be advancedafter the embolic protection device 100 is deployed to perform adiagnostic or interventional procedure. Optionally, the embolicprotection device 100 can be retracted and withdrawn with the deliverycatheter 126 after the diagnostic or interventional procedure has beencompleted. Alternatively, the delivery catheter 126 can be withdrawn,leaving the embolic protection device 100 in place.

FIG. 8 shows the embolic protection device 100 implanted in a patient'saortic arch with the delivery catheter 126 completely withdrawn. Theupstream end of the embolic protection device 100 is preferably locatedupstream of the aortic arch vessels and downstream end of the embolicprotection device 100 is preferably located downstream of the aorticarch vessels, as shown. Alternatively, the entire embolic protectiondevice 100 can be located in the ascending aorta upstream of the aorticarch vessels. Potential emboli 144 are captured in the collectionchamber 103 between the conical inner structure 104 and the cylindricalouter structure 102.

The catheter port 106 in the embolic protection device 100 allowstransluminal aortic access for performing future surgeries and otherinterventional or diagnostic procedures. FIG. 9 shows a guidewire 146passing through the catheter port 106 to guide a diagnostic ortherapeutic catheter 148 through an implanted embolic protection device100. The conical inner structure 104 assists by funneling the guidewire146 into the catheter port 106. The catheter 148 is then advancedthrough the catheter port 106 over the guidewire 146.

FIG. 10 shows a catheter-based interventional procedure being performedwith the implanted embolic protection device 100 in place. In thisexample, a coronary guiding catheter 148 has been advanced through thecatheter port 106 of the embolic protection device 100 to selectivelycatheterize one of the coronary arteries. A therapeutic catheter 150 hasbeen advanced through the guiding catheter 148 for performing a coronaryintervention.

FIG. 11 shows an embolic protection device 100 in a retracted conditionfor removal from the patient's aorta. A retrieval catheter 152 has beeninserted intraluminally over a guidewire 146 to the location of theembolic protection device 100. Optionally, the guidewire 146 andretrieval catheter 152 may be inserted into the conical inner structure104 and/or through the catheter port 106. A hook 154 on the distal endof an elongated member 156 within the retrieval catheter 152 has engagedthe pull loop 122 on the embolic protection device 100. The hook 154 mayengage the pull loop 122 through a distal port or a side port 158 on theretrieval catheter 152. The hook 154 and the pull loop 122 are withdrawninto the retrieval catheter 152, pulling on the connecting member 118and causing the retraction members 116, 120 to tighten and collapse theembolic protection device 100 to a smaller diameter with the embolicdebris 144 trapped inside the retracted embolic protection device 100.

In one particularly preferred embodiment, the embolic protection device100 is configured to close the upstream end 108 of the cylindrical outerstructure 102 first to assure that any captured emboli do not migrateout of the collection chamber 103. This can be accomplished by providingtwo separate pull loops 122 for selectively retracting the upstream anddownstream retraction members 116, 120. Alternatively, it can beaccomplished by configuring the connecting members 118 so that, when thepull loop 122 is pulled, the upstream retraction member 116 isautomatically tightened before the downstream retraction member 120 istightened.

The entire embolic protection device or a portion of it may be coatedwith an antithrombogenic coating, for example a bonded heparin coating,to reduce the formation of clots that could become potential emboli.Alternatively or in addition, the embolic protection device or a portionof it may have a drug-eluting coating containing an anti-inflammatory orantistenosis agent.

FIGS. 12 and 13 show an inflatable embodiment of the embolic protectiondevice 100 of the present invention. FIG. 12 shows the embolicprotection device 100 in an uninflated condition, and FIG. 13 shows theembolic protection device 100 in an inflated condition. The embolicprotection device 100 is similar in structure to the embodimentspreviously described, with the notable difference that the filter meshmaterial is supported on an inflatable support framework 160. Theinflatable support framework 160 includes a proximal inflatable toroidalballoon 162 and a distal inflatable toroidal balloon 164, and optionallyincludes one or more inflatable longitudinal struts 166, 168. Theframework 160 may include one or more radial struts 172, 174 to supportthe narrow upstream end of the conical inner structure 104 where thecatheter port 106 is located concentrically within the cylindrical outerstructure 102. Optionally, the radial struts 172, 174 may also beinflatable. The inflatable support framework 160 may be constructed of acompliant, semicompliant or noncompliant polymer material or acombination thereof. An inflation tube 170 extends out of the patient'sbody for inflating and deflating the inflatable support framework 160with a fluid medium, such as saline solution or carbon dioxide gas.Optionally, the inflation tube 170 may be detachable from the inflatablesupport framework 160 and a valve 176 may be provided for maintainingthe framework 160 in an inflated condition once the inflation tube 170has been detached.

The uninflated embolic protection device 100 may be delivered into thepatient's aorta on a guidewire or delivery catheter and/or inside of adelivery sheath. Once, the embolic protection device 100 is in theproper position within the aortic arch, the inflatable support framework160 is inflated through the inflation tube 170. At least the distalinflatable toroidal balloon 164, and optionally the proximal inflatabletoroidal balloon 162, makes a seal with the aortic wall when inflated sothat blood flow will be directed into the collection chamber 103 andthrough the filter mesh material to capture any potential emboli. If theembolic protection device 100 is intended for short term use, theproximal end of the inflation tube 170 may be left exposed at theinsertion site. Alternatively, if the embolic protection device 100 isintended for long term use, the inflation tube 170 may be detached fromthe inflated embolic protection device 100. As another alternative, theproximal end of the inflation tube 170 may be buried under the patient'sskin to allow later access for deflating and withdrawing the embolicprotection device 100.

When the embolic protection device 100 is no longer needed, theinflatable support framework 160 is deflated and the embolic protectiondevice 100 is withdrawn from the patient. Preferably, the embolicprotection device 100 is configured such that the distal toroidalballoon 164 on the upstream end of the collection chamber 103 deflatesfirst to effectively capture any potential emboli inside of thecollection chamber 103. Other mechanisms described herein may also beused to assist in retracting the embolic protection device 100.

Other mechanisms may be employed for deploying and/or retrieving theembolic protection device 100. For example, the embolic protectiondevice 100 can be elongated in the longitudinal direction to cause itcontract radially. Releasing the tension on the embolic protectiondevice 100 allows it to contract in the longitudinal direction and toexpand radially for deployment. A retrieval catheter can be configuredto apply longitudinal tension to the embolic protection device 100 tocollapse it radially for withdrawal from the patient. Alternatively orin addition, the embolic protection device 100 can be twisted or wrappedto cause it contract radially. Releasing the embolic protection device100 allows it to untwisted or unwrapped and to expand radially fordeployment. A retrieval catheter can be configured to apply torque tothe embolic protection device 100 to twist or wrap it to collapse itradially for withdrawal from the patient. These mechanisms may also beused in combination with the methods described above, such as thoseusing retraction members or an inflatable support framework, to deployand/or retrieve the embolic protection device 100.

Alternate embodiments of the embolic protection device 100 may combinefeatures of the embodiments described herein to accomplish the sameends. For example, an embolic protection device 100 may be constructedwith a single hoop 112 or inflatable toroidal balloon 164 on theupstream end of a cylindrical or conical outer structure 102 in contactwith the vessel wall to anchor the device and to direct blood flow intothe emboli collection chamber 103. The downstream end of the outerstructure 102 may be constructed without a hoop or toroidal balloon, oralternatively with a smaller diameter hoop or toroidal balloon, as it isnot critical for the downstream end of the embolic protection device 100to contact or make a seal with the vessel wall. The inner conicalstructure 104 may be constructed with self-supporting filter meshmaterial or the filter mesh material may be supported on a framework ofresilient struts and/or inflatable struts.

The embolic protection device of the present invention can also be usedfor embolic protection of other organ systems. For example, an embolicprotection device can be deployed in the patient's descending aorta forpreventing embolic particles in the aortic blood flow from entering therenal arteries and embolizing in the patient's kidneys.

While the present invention has been described herein with respect tothe exemplary embodiments and the best mode for practicing theinvention, it will be apparent to one of ordinary skill in the art thatmany modifications, improvements and subcombinations of the variousembodiments, adaptations and variations can be made to the inventionwithout departing from the spirit and scope thereof.

1. A method for advancing a catheter over an aortic arch, said methodcomprising: providing an embolic protection device comprising acylindrical outer sleeve and a conical inner structure, wherein a widebase of the conical inner structure is attached to a downstream end ofthe cylindrical outer sleeve and a narrow port of the conical innerstructure is located at an upstream end of the cylindrical outer sleeve;positioning the embolic protection device in the aortic arch so that thecylindrical outer structure covers the aortic vessels and the upstreamend faces the heart; and advancing the catheter from the downstream endof the embolic protection device through the port toward the heart;wherein emboli generated upstream of the emboli protection device flowinto and are trapped within a collection chamber defined at thedownstream end between the cylindrical outer structure and conical innerstructure.
 2. A method as in claim 1, wherein the inner conicalstructure comprises a mesh filter material.
 3. A method as in claim 2,wherein the cylindrical outer structure comprises a mesh filtermaterial.
 4. A method as in claim 3, wherein the mesh filter materialsof the inner conical structure and the cylindrical outer structure havethe same pore size.
 5. A method as in claim 4, wherein the pore size isin the range from 0.1 mm to 1 mm.
 6. A method as in claim 3, wherein themesh filter material of the inner conical structure is sized to stopmacroemboli and the pore size of the cylindrical outer sleeve is sizedto stop microemboli.
 7. A method as in claim 3, wherein a portion of thecylindrical outer structure away from the aortic arch vessels comprisesan impermeable material.
 8. A method as in claim 1, wherein the embolicprotection device is self-supporting in the deployed configuration.
 9. Amethod as in claim 8, wherein positioning comprises releasing theembolic protection device from a compressed condition so that the deviceself-expands within the aorta.
 10. A method as in claim 9, wherein thecylindrical outer structure and the conical inner structure compriseresilient mesh filter materials.
 11. A method as in claim 8, wherein thecylindrical outer structure and the conical inner structure comprisefilter mesh material supported by a framework.
 12. A method as in claim11, wherein the framework is resilient and the device is self-expanding.13. A method as in claim 1, further comprising retrieving the embolicprotection device, wherein the embolic material remains trapped in thecollection chamber during the retrieval.
 14. A method as in claim 13,wherein retrieving comprises retracting retraction members on theupstream and downstream ends of the emboli protection device to collapsethe device.
 15. A method as in claim 1, wherein the upstream portcomprises a resilient seal sized for the catheter.